<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>判断鼠标划入方向</title>
  <style>
  #box{width: 200px;height: 200px;border:1px solid #999;margin: 200px auto;position:relative;zoom:1;overflow: hidden;}
  #box1{height: 200px;background-color: orange;text-align: center;line-height: 200px;}
  #box2{position: absolute;left: -200px;top: -200px;width: 200px;height: 200px;background-color: red;text-align: center;line-height: 200px;}
  </style>
  </head>
  <body>


  <div id="box">
      <div id="box1">
          #box1
      </div>
      <div id="box2">
          #box2
      </div>
  </div>
<script src="../js/jquery-2.1.4.min.js"></script>
<script>
    $(function () {
        $("#box").on("mouseenter mouseleave", function (e) {
            var w = $(this).width();
            var h = $(this).height();
            var x = (e.pageX - this.offsetLeft - (w / 2)) * (w > h ? (h / w) : 1);
            var y = (e.pageY - this.offsetTop - (h / 2)) * (h > w ? (w / h) : 1);
            var dirNum = Math.round((((Math.atan2(y, x) * (180 / Math.PI)) + 180) / 90) + 3) % 4;
            /*
                dirNum:0,1,2,3 ---> t r b l
                以上代码是网友分享
                以下代码是模仿拉勾网首页的一个小效果做的
            */
            var eventType = e.type;
            var aPos = [{ left: 0, top: -200 }, { left: 200, top: 0 }, { left: 0, top: 200 }, { left: -200, top: 0 }];
            if (eventType == 'mouseenter') {
                $("#box2").css(aPos[dirNum]).stop(true, true).animate({ left: 0, top: 0 }, 200);
            } else {
                $("#box2").stop(true, true).animate(aPos[dirNum], 200);
            }
        });
    });
    </script>
  </body>
  </html>